So your new dog hasn't learned the rules of the house yet. What's going to happen when you have to go to work? It will wreck your house! You have two solutions: You can crate train your dog, or you can build it an indoor kennel---a safe haven, if you will, where it can remain comfortably when left alone.
Designate a safe, doggie-proof area for your dog. This can be a separate room or a corner in an existing room. You want to make sure the room has a window so the dog does not suffocate and is free of electrical wires or other dangerous materials you don't want your dog to reach.
If your designated area or room is carpeted, lay rubber utility mats on the floor. You can find them at most hardware stores. This will make it easier to clean up accidents or spills. It is very difficult to remove pet stains and odors from carpets!
If you are not turning a separate room into your indoor dog kennel, assemble your X-pen or multiple X-pens around the designated area and make sure the bottoms rest evenly on the mats. Make sure you and your dog can exit the area comfortably. Most X-pens are built with a wired door that can be opened and locked.
Inside your dog kennel, place a dog bed, a large dish for water and a smaller dish for dog food about a foot away from the entrance. Throw in some dog toys or chews.
In case of accidents, place newspapers on the floor or rubber mats in the dog kennel, farthest from the entrance and from the dog's bed and food area. Dogs will instinctively potty farthest from where they sleep. It is preferable to train your dog to do its business outside, but some work schedules make this impossible, especially for very young puppies who cannot hold it for more than a couple of hours. Unless you can afford a dog walker, placing newspapers in your kennel is one potty training solution.